The range and endurance of present day aircraft are limited by the amount of expendable fuel they carry. The utilization of fossil fuels necessitates a large number of mechanical and electrical devices which decrease the overall reliability of an aircraft. These include fuel cells, fuel pumps, fuel transfer pumps, level sensors, fuel level indicators, valves and piping. Further, aircraft aerodynamics are adversely affected on account of storage requirements for fuel. Normally, fuel tanks are located in aircraft wing cavities which require thicker wings. Further, aircraft performance may vary as fuel is consumed due to a shift in an aircraft's center of gravity during flight.
Nuclear power has long been considered an alternative to fossil fuel. Further, prior approaches have involved large reactors which present problems in terms of practicability.
The present invention relies upon a prior art Particle Bed Reactor (PBR) which is a high temperature gas cooled nuclear reactor. The PBR is a compact, very efficient, high capacity heater for gases which are heated directly by fissioning particulated nuclear fuel. The nuclear fuel particles are contained in fuel elements each consisting of a porous outer pipe and a smaller diameter inner porous pipe with the particulate fuel packed in the annulus formed between the porous pipes. The gas flows radially through the outer porous pipe, over the fuel particles, then through the inner pipe into its axial channel and out of the channel to do work. The fuel elements are arranged in generally concentric circles around a central fuel element in a moderator matrix to form the reactor core. The reactor core is contained in an appropriately configured pressure vessel to form the reactor. Reactor safety is assured by insertion of safety rods when the reactor is not operating. To operate the reactor, the safety rods are withdrawn and reactor reactivity is controlled by varying the depth of the control rods within the reactor.